Power drive mechanism



1 P. E. JAQUlSH; JR 3,403,513

POWER DRIVE MECHANISM Filed Feb. 3, 1967 Y ll 52 23 I *2 N 2ooo 5;!

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ATTORNE Y United States Patent 3,403,513 POWER DRIVE MECHANISM Paul E.Jaquish, Jr., Bay Village, Ohio, assignor to General Motors Corporation,Detroit, Mich., a corporation of Delaware Filed Feb. 3, 1967, Ser. No.613,905 7 Claims. (CI. 60-53) ABSTRACT OF THE DISCLOSURE A hydraulicdrive including a pump and variable displacement motor incorporating aspeed-responsive drive ratio control valve movable against a spring toincrease the motor capacity and including means responsive to increasein torque being transmitted to decrease the force effect of the springto control drive ratio as a function both of speed of rotation of thepump housing and torque being transmitted.

Specification An object of this invention is to provide a drivemechanism wherein the drive ratio is controlled both as a function ofspeed of rotation of the output member and torque being transmitted bythe output member.

Another object of this invention is to provide in a drive mechanism adrive ratio control valve controlled as a function of speed of rotationof the valve and the torque being transmitted by the drive mechanism.

A further object of this invention is to provide a drive mechanismincorporating a pump and motor having a variable displacement whereinthe motor displacement is controlled as a function of speed of rotationof a pump element and as a function of torque loading of the pumpelement.

A more specific object of this invention is to provide in a drivemechanism of the type described a speed-responsive valve movable againsta biasing means to increase the motor capacity together withtorque-responsive means effective with increase in torque beingtransmitted to decrease the effect of the valve biasing means to permitchange of drive ratio as a function of both speed of rotation of thepump housing and torque being transmitted through the pump housing.

A more specific object of this invention is to provide in a drivestructure of the type described a speed-responsive valve movable againsta spring to increase the pump capacity together with torque-responsivemeans responsive to increase in torque to move a valve seat to decreasethe effective force of the valve spring and conversely, movable upondecrease in torque to increase the force effect of the valve spring uponthe speed-responsive valve.

These and other objects and advantages of this invention will beapparent from the following description and claims taken in conjunctionwith the accompanying drawings in which:

FIGURE 1 is a longitudinal sectional view of a drive structureconstructed in accordance with the principles of this invention;

FIGURE 2 is an elevational view taken along the line 2-2 of FIGURE 1;and

FIGURE 3 is a set of curves illustrating the representative torquerequirement in relation to input speed, the operation wherein thecontrol valve is solely speed-responsive, and the operation of thepresent invention wherein the valve is both speed and torque controlled.

Referring to FIGURE 1 there is shown a drive mechanism constructed inaccordance with the principles of this invention. The drive unitincludes a constant displace- 'ice ment pump indicated generally by thenumber 10 and a hydraulic motor indicated generally by the number 7.Pump 10 is a vane-type pump including a rotor 11, vanes 12 and a camring 13. Passages 14 extend through rotor 11 adjacent the inner ends ofthe vanes for urging the vanes outwardly against cam ring 13 with fluidpressure to assist centrifugal force during rotor rotation. A twopartpump housing 15, 16 encloses the vaned rotor and cam ring, being pinnedto cam ring 13 by pins 17 and is secured together by studs 18. Apressure plate 19 is disposed between rotor 11 and housing section 16. Aspring 20 biases pressure plate 19 and rotor 11 axially against housingsection 15. Rotor 11 is splined at 9 to an engine driven crank shaft 8such that pump rotor 11 will be driven at engine speed whenever theengine (not shown) is operated.

A hub 21 extends axially from housing part 15 and is coupled directly toa rotor of motor 7 having two parts 22, 23. The rotor carries slidablevanes 24 which operate a circular cam ring 25. A motor housing 26 whichis fixed against rotation by any suitable means, as by bolting to theengine (not shown), encloses the motor. A plate 27 closes off the end ofthe housing 26 adjacent the engine and is retained on housing 26 by asnap ring 28. A pressure plate 29 disposed between the motor rotor andend plate 27 is slidable axially and functions as a piston for biasingthe two part rotor 22, 23 against the web of the motor housing 26. A pin30 carried by pressure plate 29 extends into a recess 31 in cam ring 25and a pin 32 pins pressure plate 29 to housing 26. Cam ring 25 is thuspermitted radial travel but is anchored against rotation. Thedisplacement of the motor may be varied by changing the radial positionof cam ring 25. A spring 33 biases cam ring 25 towards its positionshown, concentric with the motor rotor and power input shaft 8.

A spring seat 34 screw-threaded in the motor housing may be rotatedrelative to the housing to adjust the compressive force of spring 33. Afluid pressure-responsive bellows 35 is positioned between cam ring 25and housing 26, diametrically opposite spring 33 for moving cam ring 25eccentrically of the motor rotor to increase the fluid displacement orthe motor. Passages 36 in the motor rotor admit pressure beneath motorvanes 24 for biasing them outwardly against cam ring 25.

Between pump pressure plate 19 and pump housing portion 16 is areservoir 40 for fluid which is circulated through the pump and motorand which is used to actuate bellows 35. Fluid inlet to the pump isthrough two diametrically shaped grooves 42 in the rotor side ofpressure plate 19 and connected to reservoir 40 by passage 41 in thepressure plate. Circumferentially spaced from each inlet pocket 42, andon the opposite side of the pump rotor, is the pump outlet in the formof two diametrically spaced pockets 43 in the housing part 15.Connecting passages 44, 45, 46, and 47 extend through housing part 15,motor rotor parts 22, 23 and motor pressure plate 29, respectively, toconnect pump pockets 43 with an annular chamber 48 between pressureplate 29 and end plate 27 of the motor. Fluid pressure thus delivered tochamber 48 from the pump during operation causes pressure plate 29 tobias the motor rotor against the web of motor housing 26. The inlet tothe motor is in the form of a plurality of circumferentially spacedpockets (one shown at 49) on the rotor side of the motor pressure plate29 and these pockets are connected with the annular space 48 by passages50 through pressure plate 29. The outlet for the motor is in the form ofan equal number of circumferentially spaced pockets in the web of themotor housing 26, one being shown at 51. Additional passages 52 in themotor housing and a passage 53 in the pump housing part 15 connect topassage 64 through the pump rotor and these passages 64 connect withpassages 39 through pump pressure plate 19 leading back to reservoir 40.

Oil or other fluid may be used as the working fluid, and is pumped tothe motor and returned to the pump reservoir in response to relativerotation of the engine crankshaft and housing -16. When the fluiddisplacement of the motor is zero, that is when the motor cam ring isconcentric with the rotor 22, 23, all reaction from the pump pressure istaken directly by the pump cam ring 13 and applied by it to the pumphousing 15-16 such that the speed of rotation of the pump housing isdriven at a speed having a constant ratio to crankshaft speed. As thefluid displacement of the motor increases by shifting its cam ring 25eccentrically of the motor rotor, less of the pump pressure reaction istaken directly by pump cam ring 13, and is instead applied against therotor 22, 23 of the motor in effecting its rotation as a result of thepump pressure delivered to the chamber 55 of the motor between the vanedmotor rotor 22, 23 and the motor cam ring 25.

Actuation of bellows to effect such eccentric positioning of motor camring 25 is accomplished by applying hydraulic pressure from the pump forexpanding bellows 35. Passage means for expanding bellows 35 includes apocket 56 in the motor housing wall communicating with the interior ofbellows 35, passages 57, 58, 59, 60 and 61 provided in motor pressureplate 29, rotor parts 22, 23, and pump housing parts 15, 16. Betweenpassage 61 and reservoir chamber is a connecting passage 62 in the formof a bore of a valve body 63 formed integrally. with pump housing part15. Bore 62 extends radially of the unit and receives a slidablecentrally apertured valve 64. In the position shown valve 64 closespassage 61 against the application of fluid pressure from reservoir 40to bellows 35. A spring 65 biases valve 64 toward its closed positionand is seated upon a plug 70 threaded into valve body 63. It will beapparent that valve 64 is centrifugally force-responsive and that atspeeds below a predetermined speed of rotation will close off passage61. By selecting a spring 65 of suflicient stiffness the valve can bemaintained in its closed position against the centrifugal force inducedby rotation of the pump housing at speeds thereof below a predeterminedspeed at which it is desired to open.

Fixed to pump housing part 16 for rotation therewith is a pulley drivemember 75 providing -a seat for a resilient member 76 which carries apulley sheave 77. More specifically, pulley sheave 77 is connected topump housing portion 16 by a resilient connector 76. Member 77 isillustrated as an annular ring having rubber-like charac teristics andbonded to drive member 75 and the base of driven pulley sheave 77.Pulley sheave portion 77 drives a belt 78 which may drive theaccessories of a vehicle engine such as the fan, generator, powersteering pump or air-conditioning compressor, and which is thereforesubjected to variation in load depending upon the number of units beingoperated at any given time and the speed of operation of such units. Arack 80 carried by pulley sheave 77 mates with a pinion 81 formed onvalve seat plug 70. It will be apparent that due to the loading appliedto belt 78 and sheave 77 that resilient member 76 through which torqueis transmitted from member 75 to pulley sheave 77 will accommodatelimited angular rotation of pulley sheave 77 relative to pump housingpart 16. As the pulley load is increased the rack and pinion rotatesplug 70 relative to the pump housing such that the force effect ofspring 65 on valve 64 is decreased. In this manner the preload of spring65 is adjusted by torsional rotation of output drive pulley 77 such thatincrease of torque rotates the preload plug adjuster 70 to decrease thepreload on spring 65 which thereby reduces the output speed of the pumphousing 15, 16 and pulley 77. The device functions to produce a constantpower drive by decreasing the output speed as the torque beingtransmitted increases and by increasing the output speed as the torquebeing transmitted decreases. A constant power drive mechanism asdescribed will permit running of a prime mover at constant speed andwill still produce variable output torque on an as-required basisadjusting the output speed correspondingly such that the product ofspeed and torque will balance the input power to the drive mechanism.

To more particularly explain the invention, there is shown in FIGURE 3three curves A, B, C. Curve A is a curve illustrating input speed,output speed and a representative torque requirement in relation tooutput speed for a pulley driven at a fixed ratio relative to inputspeed. Curve B is a curve illustrating the operation of a device whereinthe preload of spring 65 is constant and valve 64 is solely speedresponsive to open at a predetermined speed of rotation of the pumphousing. Curve C represents the operation of the present inventionwherein the output speed of rotation of the pump housing is controlledto reduce the output speed in response to increase in torque loading. Inthe arrangement of curve B wherein the valve 64 would be solelycentrifugally operated the valve has a linear displacement as a functionof speed. In the present invention the displacement of valve 64 is anon-linear displacement corresponding to the output torque of the drivemechanism.

Assuming that valve 64 should open to meter suificient pressure toexpand bellows 35, cam ring 25 will move against spring 33 and bepositioned in eccentric relation- .ship with respect to the rotor axisand the motor rotor is caused to rotate. Since the motor rotor is fixedfor rotation with pump housing part 15, there is a feedback of torque tothe pump housing to assist in driving the accessories. The output torqueis split between that directly imparted to the pump cam ring and housingas a result of reaction to fluid pressure developed in the pump pumpingchamber and that imparted to the pump housing, resulting from drive ofthe pump housing by the motor rotor 22, 23. Valve 64 is both speedresponsive and torque responsive. An increase in speed of rotation ofvalve 64 results in increase in centrifugal force acting on valve 64tending to open the valve against spring 65 to admit fluid to bellows 35to increase the eccentricity of the motor cam ring 25. As thiseccentricity increases, the fluid displacement of the motor increaseswith the result that an increasing share of the input torque fromcrankshaft 8 is transmitted to the pump housing and pulley 77 via themotor. Insofar as the speed response of valve 64 is concerned the motorthus serves to an increasing extent with increased crankshaft speed as aby-pass for the pump such that the drive ratio between the crankshaft 8and pulley 77 decreases from unity. Insofar as the torque response isconcerned, an increase in the load driven by pulley sheave 77 will causelimited angular rotation of pulley sheave 77 relative to the pumphousing whereupon the rack and pinion 81 rotate valve plug seat 70 in avalve body 63 to decrease the preload of spring 65. Such rotation ofspring seat 70 decreases the force eifect of spring 65 to permit afurther movement of valve 64 against spring 65 (for a given speed ofrotation of the pump housing) such that the by-pass effect of the motoris increased and the speed of rotation of the pump housing decreasesrelative to increase in crankshaft speed to a greater extent than istrue in structures wherein valve 64 is solely speed responsive. Thisadditional control, wherein an increase in torque being transmittedthrough belt 78 modifies the action of valve 64, may be calibrated suchthat the power being delivered to belt 78 which is the product of torquetimes speed may be constant irrespective of variation of speed ofrotation of crankshaft 8. By weakening the force effect of spring 65 inresponse to increase in torque being transmitted the centrifugal forceacting on valve 64 is rendered more effective on valve 64 for a givenspeed of rotation, and conversely, if the torque being transmitted at agiven speed of rotation is decreased, relative angular rotation ofpulley sheave 77 relative to the pump housing will cause valve seat plug70 to rotate relative to the pump housing to increase the force effectof spring 65 to provide increased resistance to centrifugal force actingon valve 64, to speed up the speed of rotation of pulley 77 relative tocrankshaft speed for a given speed of rotation of shaft 8. In thismanner the power transmitted which is the product of speed and torquemay be made constant irrespective of variation of speed of rotation ofshaft 8.

What is claimed is:

1. In a variable ratio drive, a power input shaft, a pump, a motor, apump rotor driven by said shaft, a pump reaction member, a pump housingadapted to be driven by said pump reaction member, a motor housing fixedagainst rotation, a motor rotor fixed for rotation as a unit with saidpump housing, a pump reaction member capable of radial movement withrespect to said motor rotor, means biasing said pump reaction memberinto concentric relationship with respect to said motor rotor, fluidpressure responsive means adapted to move said motor reaction memberinto eccentric relationship with respect to said motor rotor, areservoir in said pump housing, passage means for delivering fluidpressure from said pump to said motor rotor and for returning fluid fromsaid motor to said pump reservoir, additional passage means between saidreservoir and said fluid pressure-responsive means, a valve forcontrolling said additional passage means, biasing means for positioningsaid valve to block off said additional passage means, said valve beingmovable in response to centrifugal force upon rotation of said pumphousing, a power delivery member driven by said pump housing, and meansresponsive to torque being transmitted by said power delivery member forvarying the force effect of said valve biasing means in response tovariation of torque being transmitted by said power delivery member.

2. A variable ratio drive as set forth in claim 1 wherein said valuebiasing means comprises a spring and said means for varying the forceeffect of said valve biasing means includes a spring seat carried bysaid pump housing and movable relative to said pump housing in responseto variation of torque being transmitted by said power delivery member.

3. A variable ratio drive according to claim 1 wherein said valve ismovable in response to centrifugal force to open said additionalpassage, wherein said valve biasing means includes a spring seated upona spring seat rotatable in said pump housing and movable radially withrespect to said valve upon rotation relative to said pump housing, andwherein said torque-responsive means is operatively connected to saidspring seat for rotating said spring seat relative to said pump housing.

4. A variable ratio drive as set forth in claim 1 wherein said valve isresponsive to centrifugal force upon rotation of said pump housing toopen said additional passage means, said valve biasing means comprises aspring seated upon a spring seat adapted upon rotation to move radiallywith respect to said valve and wherein said power delivery member isdriven from said pump housing by a resilient connection to said housingpermitting limited angular rotation of said power delivery member withrespect to said housing, and means operatively connecting said powerdelivery member to said spring seat for rotating said spring seat inresponse to angular rotation of said power delivery member with respectto said pump housing.

5. In a variable ratio drive, a rotatable pump housing enclosing a pumprotor, a pump reaction member fixed for rotation with said housing,a'power input shaft for driving said rotor, a fluid reservoir in saidpump, a motor having a housing fixed against rotation, a rotor fixed forrotation as a unit with said pump housing, a motor reaction memberradially movable with respect to said motor rotor, working fluid in saidreservoir, passage means for delivering fluid from said pump to saidmotor for driving said motor and for returning fluid to said reservoir,means biasing said motor reaction member into concentric relationshipwtih respect to said motor rotor, fluid pressure-responsive means formoving said motor rotor, into eccentric relationship with respect tosaid motor rotor, additional passage means between said pump reservoirand said fluid pressure-responsive means, a valve carried by said pumphousing for controlling said additional passage means, spring meansyieldably biasing said valve to block off said additional passage meansfrom said reservoir, said valve being responsive to centrifugal force inresponse to rotation of said pump housing to open said additionalpassage means to said reservoir, a valve seat for said spring meansscrew threaded into said pump housing and adapted to be rotated to varythe force effect of said spring means, a final power delivery member, aresilient drive connection between said pump housing and final deliverymember permitting limited angular rotation of said final drive memberwith respect to said pump housing in response to variation of torquebeing transmitted by said final drive member, a rack fixed to said finaldrive member, and a pinion rotatable as a unit with said valve seat andmating with said rack, said rack and pinion being effective uponincrease of torque being transmitted by said final output member torotate said valve seat to reduce the force effect of said spring meansand effective upon decrease of torque being transmitted to increase theforce effect of said spring means.

6. In a variable ratio drive, a pump including a rotatable pump housing,a pump rotor, a reaction member fixed for rotation with said-pumphousing and adapted to drive said housing in response to rotation ofsaid rotor, a power input shaft for driving said pump rotor, a motorhaving a housing fixed against rotation, a vaned rotor having vanesradially movable with respect to said rotor, a cam ring contacting saidvanes and radially movable with respect to said motor rotor, said motorrotor being connected for rotation as a unit with said pump housing, afluid reservoir in said pump housing, passage means for delivering fluidfrom said pump to said motor and for returning fluid from said motor tosaid reservoir, spring means yieldably biasing said motor cam ring intoconcentric relationship with respect to said motor rotor, fluidpressure-responsive means adapted to move said motor cam ring intoeccentric relationship with respect to said motor rotor, a controlpassage between said fluid pressureresponsive means and said reservoir,a centrifugal forceresponsive valve in said pump housing for controllingfluid flow through said control passage, a spring yieldably biasing saidvalve to block off said control passage, a spring seat movable relativeto said pump housing for varying the force effect of said spring, apower delivery member, resilient means for driving said power deliverymember from said pump housing and accommodating limited angular rotationof said power delivery member with respect to said housing, andadditional means connecting said power delivery member to said springseat for decreasing the force effect of said spring in response toincrease in torque transmitted to said power delivery member, and forincreasing the force effect of said spring in response to a drop oftorque transmitted by said power delivery member.

7. A drive structure according to claim 6 wherein said spring seat ismoved in response to variation in torque demand to maintain constantpower output irrespective of variation of speed of rotation of saidinput shaft.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.6. 20231 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,403,513October 1, 1968 Paul E. Jaquish, Jr.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, line 20, "a circular cam ringgZS." should read in a circularcam ring 25. line 49,,F'shaped" should read spaced Column 5, line 36,"value" should read valve Signed and sealed this 24th day of February1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

